Persistence Or Not Trusting?

I've been struggling with, and thinking about, something lately.

You see, I'm praying about something in particular. It doesn't matter what it is for this purpose, I'm using it as my example.

I am trying to leave a situation in God's hands (even though I will still pray about it), I mean, He is the one in control, but that's not always an easy thing to do.  My dilemma in the matter is this:  every time I pray for and about this particular situation, am I not trusting God?  Am I trying to take things into my own hands, so to speak, and continuing to pray because I really want this to be answered in a specific way, or am I just being persistent?

Jesus tells a parable in Luke 18: about a persistent widow. He wanted to show his disciples that they should always pray and not give up.

What is perplexing me, is whether or not I am actually praying about the situation and not giving up (which I am doing, I guess), being persistent, or am I just praying about it so much because I lack trust in God, in His answering my prayer?

How can you tell the difference between the two?  When are you being persistent in prayer and when are you just praying because you might not truly believe or trust that God will bring things about in answer to your prayer?

If you have any thoughts, ideas, or answers, feel free to leave them in the comment section. I'd really like to hear what you think, and hopefully someone can answer my question :).